This invention refers to a disengageable transmission device.
A U.S. patent application Ser. No. 765,024 filed Feb. 2, 1977, now U.S. Pat. No. 4,128,015 describes a device for the storage of power and its controllable, slow rate release.
In that device a gear train, supported on a lever fulcrumed on the frame, is brought in and out of engagement with a power take-off (driving) pinion and, in its engaged position, loads a spring through a rack. In its disengaged position, the gear train is moved by this spring and an escapement causes the load of the spring to be released at a slow rate.
When the escapement is locked by means of a ratchet device, also the gear train is blocked and the spring is not released.
In the device of the U.S. patent application Ser. No. 765,024, the fulcrum of the lever coincides with the axis of the last gear in the gear train, which last gear is, in its turn, keyed to a pinion meshing with the rack.
In this way, the leverage of the rack with respect to the fulcrum of the lever, due to the elastic reaction of the spring, tends to rotate the lever into its disengaged position.
Moreover, another torque is applied to the lever by the driving pinion, when it meshes with the first gear of the gear train. Such a torque also tends to rotate the lever away from the driving pinion.
A further torque is generated on the lever by the ratchet device locking the escapement.
Such torques overload the lever when it is in either of the two positions of engagement or disengagement, disturbing also the passage from one position to the other.
Consequently this gear device is not suitable for the cases in which one wants, or must, actuate the engagement and disengagement of the transmission with low energy dissipation.